code: def start(self):
      # start the thread to read frames from the video stream
      t = Thread(target=self.update, args=())
      t.daemon = True
      t.start()
      return self
  
file_path: imutils/imutils/video/pivideostream.py
imports: from picamera.array import PiRGBArray
  from picamera import PiCamera
  from threading import Thread
  import cv2
label_desc: Use image node_id 2 for calling the PiVideoStream obj's underlying member method code with example usage: obj.start() and returns: self